Reversible-circulation internal-fan kiln



June 23, 1925.

lllsil 3 Sheets-Sheet l R. THELEN Original Filed April 19, 1924,

INVENTOR. Wk? HELEN ATTORNEYS.

Fiq i REVERSIBLE CIRCULATION INTERNAL FAN KILN M J.\ M

-' 5;; a R. THELEN REVERSIBLE CIRCULATION INTERNAL FAN KILN OriginalFiled April 19, 1924 3 Sheets-Shed 2 INVENTOR. 01. HELEN BY 412M ,I. a.W a; a. ATTORNEYS;

R. THELEN REVERSIBLE CIRCULATION INTERNAL FAN KILN Original Fiied April1.9, 1,924 3 Sheets-sheaf 31 INVENTOR.

N ROL,F' THTEIEN A TTORNEYS.

Patented June 23, 1925.

UNITED STATES PATENT oF-ricE.

; ass THELEN, or MADISON, WISCONSIN,

THE PEOPLE or THE UNITED STATES.

REVERSIBLE-CIRCULATION INTERNAL-FAN KILN.

or nal application filed April 19,1924, Serial No.708,323. Divided andthis application filed llarch 7,1925. Seria1,No.14.424.

nnnzonrnn, BY MESNE ASSIGNMENTS (GRANTED UNDER THE ACT OF MARCH 3, 1883;22 STAT. L. 625.)

1, To allwhom it may concern:

Be it known that I, Rom Tureen, a citi zen of the United States ofAmerica, and an employee of the Department of Agricul- 5,=t iire,residin -in Madison, \Visconsin (whose )ost-ofiice address is ForestProducts Laboia atory, Madison, Wisconsin), have invented ;.& new andImproved Reversibio-Circulation :Ii iternal-Fan Kiln.

0,, This application is a division of an appli- ;.f.Lf3itl0D.: filedApril 19, 1924, which bears Serial Number 708,323.

e This application is made under the act o :E of March 3,1883, chapter143 (22 Stat. 625), Land; the invention herein described and ,-;i. claimed.may be used by the Government of .thejUnited States, its ofiicersand employees, .spndiby :any person in the United States B Yi thout the,payment to me of any royalty iereon. --I hereby dedicate the samet'o-the, il-cc {use of the Government and the people of the UnitedStates.

eggdtlyinvention consists in an improvement linthe design of forcedcirculation kilns or 25 chambers for drying and conditioning lumber. orsimilar material. However, its use is not limited to wood. or woodproducts. It consists in the adaptation of fans of the disk type, orsimilar types, to the. production of' .a unique internal circulation ofair and the vapor in the kiln combined with the p reductionsandregulation of the heat and the humidit within the kiln.

. This invention is illustrated in Figures 1 to 3. Figure 1 represents ahorizontal section taken .on diiicrcnt horizontal planes principally atabout the rail height. Figure'2 represents a cross-sectional elevation.Figure 3 represents a longitudinal elevation 40 .ofa portion of tlie'aircirculating and distributing system.

The principal feature which 1 claim as novel and an improvement overexisting kilns is the use and arrangement of the fans and the airdistributing system. This arrangement is such that a very fast anduniform circulation of air and vapor through the piles of lumber may besecuredand it.

permits. the periodicl evensal )fth'. direc- 0 tion-of the air movementby simply reversingthe direction of rotation of the fans. The airdistributing system provides a very uniform fiow'of air throughout thelength and breadth of the kiln and eliminates the non-uniformity ofdrying, which is one of the commonest troubles experienced in theordinary kiln. The arrangement of the fans upon a shaftextendingthroughout the length of'the kiln provides a simple means ofproducing a brisk circulation; and the elimination of comparativelysmall ducts such as those used in external blower kilns reduces verymaterially the work required to produce a given circulation; Thedifierences in air pressure required in the opera: tion of this kilnaremuch smaller than those ordinarily required in kilns employingcentrifugal blowers, and the disk fans operate very efficiently at theselow' ressures. Measurements recently made indicate that the staticpressures necessary for the suc cessful operation of this system arematerially less than one-eighth of an inch of water pressure. It ispossible, therefore, by the use of this invention to produce a verygreat and uniform cireulationof air and vapor within the kiln with avery small expenditure of power.

While it is obvious that there are many thickness and length being inhorizontal directions. Any well-known means of heating the air and .thevapor in the kiln may be used in conjunction with this invention. Whensteam pipes are used they-may be arranged beneath the lumber piles atthe sides of the kiln or in any other convenient manner. Any convenientform and arrangement of heaters may be used.

The drawings show and the specification describes steam jet pipes forincreasing the humidity, and air inlet fines and air outlet flucs withsuitable dampers for decreasing the humidity. m

While thedrawings show and the specification describes specific meansfor heating the air and the vaporin the kiln "and for regulating thehumiditfof the'air in the of the fans.

make use of any other well-known and suitable means for accomplishingthe same purrails, trucks, and track supports illustratedin the drawingsand described in the speclfication.

Referring to Figures 1, 2, and 3, which are correspondingly lettered: BBare theifans producing the circulation. Straight-bladed .disk fans arepreferable. Any type of fan, however, in which the reversal of thedirection of. rotation of the fan produces a reversal in the directionof the flow of the air current passing through the fan can be used. C isthe shaft upon which the fans are mounted. Provision is made to takecare of the expansion. and contraction of this shaft with changes in thetemperature in the kiln and to take care of the thrust This provisionconsists in equipping one of the bearings II with suitable thrust ringsor collars and equipping all of the other bearings II with any wellknownmeans for longitudinal motion. Plain bearings and roller bearingsrequire no special provision of thiskind. Certain types of ballbearingsrequire housings which permit the entire hearings to slidelongitudinally within them. DD are air inlet dampers used to regulateand control the amount of air entering the kiln from the outside. EE arethe heating coils. These may be of the return bend type or otherconvenient type. F is the steam jet pipe used to increase the humidityof the air in the kiln. Suitable openings are provided to permit theescape of the steam throughout the length of the kiln. Various othercommon and well-known arrangements may be used. GG are thelumber-supporting trucks. II arebearings for the shaft U. JJ are thetracks upon which the lumbersupporting trucks run. KK are the side wallsof the kiln. LL is the lumber to be dried. hfM are the track supports.'N is the shaft pulley. 00 are air outlet dampers for controlling theamount of air being exhausted from the -kiln. P is a belt passing overthe pulleys N and Q. Q, is the motor'pulley. R is the motor whichfurnishes the power to drive the fans. S is the switch for controllingthe speed a d rotation of the motor armature. While t e drawings showand the specification describes an electric motor, any other suitabledriving means may be used. -TT are air inlet lines in which the dampersDD are tied. UU are the air outlet fluesin which I the da apers 00 arefitted. WW are the side air passages between the piles of lumber and theside walls of the kiln. XX are the main air distributors. YY are thesecond difi'users. ZZ are the first diffusers. The plenum chambersbetween the second diffusers and the first difiusers' are the secondaryplenum chambers 126 are the fan houslugs and partitions. f are bafiies.While the drawings show an the specification describes certain specificarrangement of the fans and shaft, this invention is not limited to thisparticular arrangement, since it is obvious that its functions can beperformed in an equivalent manner with other arrangements of the fans.

The operation of the kiln is briefi follows: The lumber is placed in thekiln, the doors and all of the dampers are closed and the kiln isstarted. Steam is turned I into the coils and the steam jets are turnedon. Suitable regulating devices are provided to control and regulate thesupply of steam to the heating coils and the supply of the steam to thesteam jets. If it is found impossible to reduce the humidity to thedesired point with the steam em all turned off, the dampers DD and (lopened to allow :Eresh'airv to enter and moist air to escape. adjustedso that a humidity below that desired will besecured. The steam jets maythen supply a suflicient amount of steam to bring the humidity up to thedesired point. Assuming that the direction of ro- O are v These dampersshould be tation of the fans is such that the air and Y slight vacuum.When the direction of the circulation is reversed the upper chambers areunder vacuum and the lower ones under pressure. The velocity of the airmovement through these chambers is comparatively slow. The use of theseplenum chambers and the various sets of diffusers in the mannerindicated produces a very uniform flow of air through the length of thekiln. It is obvious that the kiln would work reasonably well with singlesets of diffusers for elach main air distributor and that still furt ierand upward through uniformity in air distribution mi ht-be secured byadding a third or even a ourth set of difiusers. The principle, ofcourse, remains the same and practical expediency will determine thebalance between increased uniformity of air distribution secured by Ithe addition lei-{mere sets of distributors- '-.-.b gween he slatsrunning the full lengthand-the loss in e'fiiciency which they cause.

; isalso obvious that any well-known form of distributor may be used.-The invention is-not restricted to the form illustrated inwhich-the-openings consist simply of spaces ioi with a great manydifferent types of forced circulatmnin dry 'kilns that it is not 1105-Isibl'e l to. secure" uniformity of distribution of th se; and vapor ifthey be handled at "high"- velcities order to produce uniform:satisfactory; circu1ation, it is essential that the. air aridvapo'r bemoved at low' ve-fv 'locitieslandithapsf ecial means be'provided forthe'uniform distribution of the air and fv vapo1fthrough the kiln. '-'.Theuse of internal -f an"s"-'-and large plenum chambers produces f-thi'sresult; since. the velocity of the .air and 'vapor-' throulghfthe fansthemselves is coniparatively. ow. and; theivelocity, in .i the plenumchambers; is so small that the yefloc'pity head can not-be measured withmanonr eters and sim ilar=. instruments usually. used fortheipiirpose.

i culation: of theairzirid theivapor inkthe vk1l1i-f.is -continiiouslyinone' direction, that portion"- o f;:tho1pile at which the air enterswin 1d fmorerapidly thanthe '-,s in ce t ejair. in'its Jpassaget roughthe l-umber picks up. moisture and thus reduces its ,ca acity. Thereversal of-the direction of t e air-circulation overcomes this defect-since that edge of each lumber pile-which was the entering aired ebefore reversa1 .becomes'the leaving air e ge-after reversal,Those'portions oi the piles which driedt fastest before reversal drymost "slowl after reversal. The reversal ofthe fcircu ation-will in;practice he done periodically every two or three days or oftcner,

'the'exact period being determined by the- .of air and vapor through thelumber to be dried, and any detailed arrangement which will accomplishthis result will be satisfac to'ry-if at the 'same time it does notconsume' an excessive amount ofpower.

Ha'vihgfullydescribed the principles j housing and ofiposite sideoriginal:

In doubleiwek newt-agar can be embodied in 'a drykiln, I claim as v e..1 for'edge stacking: a series of fans mounted between the-two rows'oflumber-pilesga shaft on which the fans are mounted forf'i i Irotation;=mea ns for rotating" saidjshaft-iin- I It has been foundthrough experience,

either direction to cause reversal-of the-cirmain air distributors, andtwo of insets for each main air-distribution- 12. Ina doubletrackdry'kfln arranged for edge stacking: a series ofzfansmo'unted hetween the two rows oflurnber' piles a shaft on which the fans aremountedfor rotation;

means for rotating said shaft'fin either-(ii? rection to causereversalofthe circulation air inlet flues -'anddamperedair outlet fines;

and an. air distributingsystein'comprising fan housing and 'pa'rtitionfor each fan, two

main air distributors; v and two sets of 'dif-' fusers for each-main airdistributor. T

ofa'ir and vapor in said kilu.;:dampered 3. In a double track dry kilnarranged comprising fan housing and partition for each fan, two main airdistributors;- and two sets of diffusers, for tributmz 3 e. In a doubletrack dry kiln arranged'for each main air disiedge'istackingi a:"series,ofiansqmounted between jthe two-rows of lumber piles; a"shaft-on which the fans are mounted for rotation; meansv for rotatingsaidishait in o the kiln and edgestacking: a series of fans mountedbetween the two rows of lumber piles; a shaft on which the fans aremounted for-rotation;- means-for rotating said shaft in either di-'rection to cause reversalof-the circulation of air and vapor insaidkiln; dampcred air inlet fines and dampered air outlet-fines; means forheating the kiln and its contents; and an air distr butingsystemcomprising fan housing and partition for each fan, two main airdistributors, and two sets of diffusers for each main air-distributor.

February 1%), 1925.

fioo

as ,culation of .air and vapor in'said and. an aindistributin'gsystemcompnsingnfan artitionfor each ifan, two

